<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>

        // function sum(n) {
        //     if (n == 1) return 1
        //     return sum(n - 1) * n
        // }
        // console.log(sum(prompt('数字')))


        // function fn(n) {
        //     if (n == 1) return 1
        //     if (n == 2) return 1 / 2
        //     return fn(n - 2) + 1 / n
        // }
        // console.log(fn(4))




        function fn(n) {
            if (n == 1 || n == 2) return 1
            return fn(n - 1) + fn(n - 2)
        }
        console.log(fn(10))

    </script>
</body>

</html>